<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        alert("Hello JavaScript")
    </script>
    <input type="button" value="点击我一下" onclick="alert('haha')">
</body>
</html>